We have designed peptides with particular characteristics 1) binding and dissocation rates appropriate for subsecond analysis of macromolecular assembly; 2) introduction of the fluorophore into regions of the receptor binding pocket which undergo conformational changes; and 3) high afinity antagonists to the receptor. A family of formyl peptides with fluorescein isothiocyanate conjugated at positions 2 through 7 has been generated and their binding to receptors has been examined. (Manuscript in preparation). Receptor antagonists are being evaluated as a new class of anti-inflammatory drugs through SBIR support.